AArch64A57FPLoadBalancing.cpp: Define ColorNames in !NDEBUG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215226 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp

@@ -107,7 +107,9 @@ namespace {
 /// A "color", which is either even or odd. Yes, these aren't really colors
 /// but the algorithm is conceptually doing two-color graph coloring.
 enum class Color { Even, Odd };
+#ifndef NDEBUG
 static const char *ColorNames[2] = { "Even", "Odd" };
+#endif
 
 class Chain;